The present invention relates to a linear motor for a fixed feedrate and high-speed position, for which small thrust ripple, small yawing of a mover, and small pitching are required.
In conventional types of linear motors, there is a type in which concentrate-wound armature coils are disposed without being overlapped. Since no cogging force is generated, such a type is suitable for use in which a small speed ripple is required. Also, the insulation thereof is easy because it is of a simple structure in which concentrate-wound armature coils are disposed without being overlapped, and it is possible to apply the type for use in which the voltage is 200V.
FIG. 6 through FIG. 8 show a linear motor according to the prior art. FIG. 6 is a front elevational sectional view in which the linear motor is observed from the advancing direction of a mover thereof, FIG. 7 is a plan sectional view taken along the line Axe2x80x94A in FIG. 6, and FIG. 8 is a side elevational view showing an armature element.
In FIG. 6 through FIG. 8, a linear motor 1 is composed of a mover 2 and a stationary part 3. The mover 2 consists of a so-called coreless type armature element 4 and an armature element supporter 5 having the above-described armature element 4 attached thereto. The above-described armature elements 4 are provided in a plurality, for example, six concentrate-wound armature coils 6 are disposed in a row in the advancing direction, and are molded with resin.
Also, the above-described armature coils 6 have a 3-phase, 3-coil and 4-pole basic structure, and the coil pitch Pc of the armature coils 6 is 4/3xc3x97Pm. The six armature coils 6 are disposed in order of U, W and V from the left side on the paper (page).
The profile of the above-described concentrate-wound armature coils 6 is, as shown in FIG. 8, shaped so that two coil sides facing secondary sides 8a and 8b and mainly generating thrust are made parallel to each other. And, these six armature coils 6 are disposed in a row in the advancing direction.
Further, the stationary part 3 has secondary sides 8a and 8b composed of permanent magnets and acting as so-called magnetic field poles and secondary side supporters 9a and 9b acting as so-called back yokes, to which the above-described secondary sides 8a and 8b are attached. The permanent magnets that constitute the above-described secondary sides 8a and 8b are disposed with a pitch Pm shifted from a permanent magnet adjacent to each other so that these have a different polarity, and are disposed so that permanent magnets facing each other have a different polarity. In addition, the above-described secondary sides 8a and 8b and the above-described armature elements 4 are disposed in parallel to each other in the advancing direction facing each other, and two secondary side supporters 9a and 9b are linked with each other and supported by a supporting member 10.
However, the prior art has the following problems.
(1) Since armature coils of different phases are adjacent to each other, there is a concern that defective insulation may arise where the armature coils are used with high voltage such as 200V.
(2) In order to increase insulation properties, it is necessary to place an insulating substance between the armature coils, wherein assembly becomes cumbersome and production cost thereof is increased.
(3) Since concentrate-wound armature coils are used, thrust ripple may occur.
The present invention was developed to solve such problems, and it is therefore an object of the invention to provide a linear motor, which can be easily assembled, having satisfactory insulation between armature coils and very small thrust ripple.
In order to solve the above-described problems, the invention is such that a linear motor, which is excellent in insulation between armature coils, easy to assemble and very small in thrust ripple, comprises a secondary side supporter attached with a second side consisting of a plurality of magnetic field poles, and an armature element supporter facing the secondary side via clearance and provided with an armature element having a plurality of concentrate-wound armature coils, wherein the secondary side and the armature element are disposed facing each other and in parallel in the advancing direction, wherein field poles in the secondary side are disposed in the advancing direction of a mover with adjacent poles differing for each Pm pitch, and a plurality of armature coils are disposed in an array in the advancing direction of the mover for each of the respective Pc pitches. Further, the above-described coil pitch Pc is made into Pc=5/3xc3x97Pm, and the above armature coil is formed of two layers at both left and right sides, and the armature coil between the two layers is disposed with a shift of n/6xc3x97Pm (n is an integral number excepting 3).
As described above, the invention brings about the following effects.
(1) Since the concentrate-wound armature coils are disposed apart from each other with a prescribed clearance, satisfactory insulation can be brought about even with high voltage specifications of 200V.
(2) Since it is not necessary to place any insulating substance between the armature coils and assembly is easy, the production cost thereof can be decreased.
(3) Since armature coils are disposed to shift to both left and right sides of the armature element, the phase belt can be distributed, it is possible to decrease the thrust ripple resulting from unevenness in magnetization of magnetic field poles such as a permanent magnet and positional shift thereof.